1. Field of the Invention
The invention relates generally to motors of the type that are used within electrical submersible pumps (ESP's). In particular aspects, the invention relates to subsurface motors having fiber optic measurement or monitoring capabilities.
2. Description of the Related Art
Electrical submersible pumps (ESPs) are routinely used in the production of hydrocarbon from wells. A typical ESP includes a downhole motor that converts the mechanical power to operate a pump and associated components, such as a gas is separator. Downhole motors include a stator and a rotor that is rotationally moveable with respect to the stator. A housing surrounds the stator and rotor.
The use of fiber optic sensors within subsurface motors of this type is discussed in U.S. Pat. No. 6,888,124. The use of fiber optic sensors within the sealed winding chambers of the stator of the motor is discussed in U.S. Patent Publication No. 2011/0002795 by Brookbank. Because U.S. Patent Publication No. 2011/0002795 is owned by the assignee of the present application, U.S. Patent Publication No. 2011/0002795 is herein incorporated by reference in its entirety. Brookbank, the optic fibers are located within the winding chambers alongside electrical conductors that pass through the winding chambers. The fiber is disposed through the winding chambers by looping it through substantially opposing sides of the stator. This permits the fiber to provide two parallel legs. Bending or deformation of the stator will place one of the opposing legs in tension and the other in compression. Optical discontinuities on each of the legs will be moved axially, and the detection of this relative axial movement allows measurement of bending or deformation of the stator.
The winding chambers of a stator are typically filled with an epoxy sealant during manufacture in order to seal in the winding wiring in place. The inventors have concludes that this sealing largely precludes the operation of these optic fibers to perform single point or distributed point sensing of operational parameters. Also, it is difficult to remove and replace a fiber from the winding compartment due to epoxy sealing.